Figure 2.

Biological metabolism versus industrial metabolism. The upper part of the figure sketches the basic metabolic cycle of the biosphere: a sustainable sequence of biochemical reactions for building (anabolism) and dismantling (catabolism) biomass and other bio‐compounds on the basis of available C, N and P species (and to a lesser extent others like Fe etc.) obtainable in the biosphere. The lower part outlines in a super‐simplified form the action of the so‐called Industrial metabolism (Ayres, 1994). This involves the integrated collection of human‐made physical and chemical processes that transform raw materials and (generally non‐renewable) energy into products, leaving wastes, e.g. CO₂ and recalcitrant products and materials) along the way. The interplay between biological cycles and industrial processes at global scale was a popular topic in the late 1970s (de Rosnay, 1979). Alas, the current state of affairs makes such an industrial metabolism – and it is associated industrial ecology (Allenby, 2006) ultimately unsustainable. The notion of transmetabolism discussed in this article attempts to overcome the breach between the natural and the human‐made chemical domains by bridging the two with new reactions and rationally delivering them at a global scale by means of deeply engineered biological agents.